From a117836ed6bbbc750830a96647da88d5506e69f8 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 14 Feb 2021 13:06:50 +0000
Subject: Construct an Arc from three points

---
 game/network/rail.cpp |  2 +-
 utility/maths.cpp     | 21 +++++++++++----------
 utility/maths.h       |  4 ++--
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/game/network/rail.cpp b/game/network/rail.cpp
index 299c647..1ed59bd 100644
--- a/game/network/rail.cpp
+++ b/game/network/rail.cpp
@@ -79,7 +79,7 @@ RailLinkStraight::RailLinkStraight(NodePtr a, NodePtr b, const glm::vec3 & diff)
 }
 
 RailLinkCurve::RailLinkCurve(const NodePtr & a, const NodePtr & b, glm::vec2 c) :
-	RailLinkCurve(a, b, {c.x, a->pos.y, c.y}, create_arc(!c, a->pos, b->pos))
+	RailLinkCurve(a, b, {c.x, a->pos.y, c.y}, {!c, a->pos, b->pos})
 {
 }
 
diff --git a/utility/maths.cpp b/utility/maths.cpp
index 5cae411..e36c91e 100644
--- a/utility/maths.cpp
+++ b/utility/maths.cpp
@@ -39,15 +39,16 @@ normalize(float ang)
 	return ang;
 }
 
-Arc
-create_arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p)
+Arc::Arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p) :
+	Arc([&]() -> Arc {
+		const auto diffa = e0p - centre3;
+		const auto diffb = e1p - centre3;
+		const auto anga = flat_angle(diffa);
+		const auto angb = [&diffb, &anga]() {
+			const auto angb = flat_angle(diffb);
+			return (angb < anga) ? angb + two_pi : angb;
+		}();
+		return {anga, angb};
+	}())
 {
-	const auto diffa = centre3 - e0p;
-	const auto diffb = centre3 - e1p;
-	const auto anga = flat_angle(diffa);
-	const auto angb = [&diffb, &anga]() {
-		const auto angb = flat_angle(diffb);
-		return (angb < anga) ? angb + two_pi : angb;
-	}();
-	return {anga, angb};
 }
diff --git a/utility/maths.h b/utility/maths.h
index 31f5960..572268a 100644
--- a/utility/maths.h
+++ b/utility/maths.h
@@ -8,6 +8,8 @@
 struct Arc : public std::pair<float, float> {
 	using std::pair<float, float>::pair;
 
+	Arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p);
+
 	float
 	operator[](unsigned int i) const
 	{
@@ -44,6 +46,4 @@ arc_length(const Arc & arc)
 
 float normalize(float ang);
 
-Arc create_arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p);
-
 #endif
-- 
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